KVM: nVMX: Filter out all unsupported controls when eVMCS was activated

Windows Server 2022 with Hyper-V role enabled failed to boot on KVM when
enlightened VMCS is advertised. Debugging revealed there are two exposed
secondary controls it is not happy with: SECONDARY_EXEC_ENABLE_VMFUNC and
SECONDARY_EXEC_SHADOW_VMCS. These controls are known to be unsupported,
as there are no corresponding fields in eVMCSv1 (see the comment above
EVMCS1_UNSUPPORTED_2NDEXEC definition).

Previously, commit 31de3d2500e4 ("x86/kvm/hyper-v: move VMX controls
sanitization out of nested_enable_evmcs()") introduced the required
filtering mechanism for VMX MSRs but for some reason put only known
to be problematic (and not full EVMCS1_UNSUPPORTED_* lists) controls
there.

Note, Windows Server 2022 seems to have gained some sanity check for VMX
MSRs: it doesn't even try to launch a guest when there's something it
doesn't like, nested_evmcs_check_controls() mechanism can't catch the
problem.

Let's be bold this time and instead of playing whack-a-mole just filter out
all unsupported controls from VMX MSRs.

Fixes: 31de3d2500e4 ("x86/kvm/hyper-v: move VMX controls sanitization out of nested_enable_evmcs()")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210907163530.110066-1-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx/evmcs.c b/arch/x86/kvm/vmx/evmcs.c
index 0dab1b7..ba6f99f 100644 (file)
--- a/arch/x86/kvm/vmx/evmcs.c
+++ b/arch/x86/kvm/vmx/evmcs.c
@@ -353,14 +353,20 @@ void nested_evmcs_filter_control_msr(u32 msr_index, u64 *pdata)
        switch (msr_index) {
        case MSR_IA32_VMX_EXIT_CTLS:
        case MSR_IA32_VMX_TRUE_EXIT_CTLS:
-               ctl_high &= ~VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL;
+               ctl_high &= ~EVMCS1_UNSUPPORTED_VMEXIT_CTRL;
                break;
        case MSR_IA32_VMX_ENTRY_CTLS:
        case MSR_IA32_VMX_TRUE_ENTRY_CTLS:
-               ctl_high &= ~VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL;
+               ctl_high &= ~EVMCS1_UNSUPPORTED_VMENTRY_CTRL;
                break;
        case MSR_IA32_VMX_PROCBASED_CTLS2:
-               ctl_high &= ~SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
+               ctl_high &= ~EVMCS1_UNSUPPORTED_2NDEXEC;
+               break;
+       case MSR_IA32_VMX_PINBASED_CTLS:
+               ctl_high &= ~EVMCS1_UNSUPPORTED_PINCTRL;
+               break;
+       case MSR_IA32_VMX_VMFUNC:
+               ctl_low &= ~EVMCS1_UNSUPPORTED_VMFUNC;
                break;
        }
 

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 0c2c0d5..f7eb0ce 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1837,10 +1837,11 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
                                    &msr_info->data))
                        return 1;
                /*
-                * Enlightened VMCS v1 doesn't have certain fields, but buggy
-                * Hyper-V versions are still trying to use corresponding
-                * features when they are exposed. Filter out the essential
-                * minimum.
+                * Enlightened VMCS v1 doesn't have certain VMCS fields but
+                * instead of just ignoring the features, different Hyper-V
+                * versions are either trying to use them and fail or do some
+                * sanity checking and refuse to boot. Filter all unsupported
+                * features out.
                 */
                if (!msr_info->host_initiated &&
                    vmx->nested.enlightened_vmcs_enabled)